1. Field of the Invention
This invention relates to a medical device having a plastic cylinder that is uniquely decorated. More particularly, this invention relates to an improved scale on a plastic syringe containing protruding volume measuring scale marks and indicia. These protrusions provide tactile readability of the scale and slip-resistant holding of the syringe barrel.
2. Description of Prior Art
Syringes usually contain volume measuring indicia on the side of the barrel to indicate the volume of liquid contained within the syringe barrel. It is desirable for convenience and preventing medical error to provide volume measuring indicia which are clear and easy to read. The need for readable graphics on a syringe barrel is especially important to diabetics who, after many years of affliction, suffer various side effects such as faulty vision. Diabetics also are believed to suffer from temporary periods of blurred vision. There is also a need to provide slip-resistant holding of the syringe barrel. This need is especially seen in the geriatric patient who self-administers medication. To this end, the scale, scale marks, and volume measuring indicia are important features of the syringe barrel.
There are many ways to manufacture a syringe with a scale. Printing or decorating plastic objects in general with indicia is well known in the art. Flexographic printing is used for printing over films. Offset printing is used for bottles, jars and tubes. Silk-screen printing is used for printing small quantities of parts or for items where an embossed effect is required. Hot stamping is used to engrave the decoration into the plastic part. Hot stamping is best suited for bright or strong colors.
Labeling, such as paper, foil, and fabric can also be used to print or decorate a plastic object. These labels can be printed on by a variety of techniques. The most widely used method of printing on labels is called letterpress. This technique permits good color control, with clear, sharp detail. A variation of this process is called letterset in which the printing is transferred from the plate to a rubber roller and then to the paper or other printed medium. A process called lithography is particularly suited to print on foil. (See Joseph F. Hanlon, Handbook of Packing Engineering, 1984, McGraw-Hill, pp. 8.9-8.10 and 12.3-12.8).
Other methods for printing or decorating plastic objects include pad printing where a rubber stamp or tub picks up an image on an ink filled die and transfers the image to the plastic object. Another printing method is called gravure printing. This type of printing is typically used for high volume production.
A common problem with the previously described printing or decorating methods is that they are secondary operations. The syringe must first be manufactured and then the scale is added in a totally different operation or secondary operation. This secondary operation adds cost to the product. Another common problem with the previously described methods is that the printing requires tight precision in positioning the scale on a syringe barrel. In addition, over time, the printing may wear or rub off. Also, certain colors may be limited in each printing or decorating methods. For diabetics with vision problems, a raised scale may be desirable to provide a tactile sensation or tactile readability of the scale and provide slip-resistant holding of the syringe. Current printing techniques that could emboss a scale cannot currently be used in high volume production.
In many printing techniques, like gravure printing, a decoration such as a scale cannot be printed 360.degree. around a cylindrical object. Using a flat foil alone with printed indicia to alleviate this problem has several disadvantages. These disadvantages include the potential of an alignment problem when the foil is wrapped around the plastic object. For a syringe, printing the scale containing the volume measuring indicia from about 1.degree. to about 360.degree. around the syringe would give several advantages. First, it would assist diabetics with vision impairments to correctly read the volume measuring indicia. Second, it would facilitate easier filling and dispensing by the healthcare professional. However, gravure printing techniques, like the other methods previously mentioned, does not allow printing 360.degree. around a cylindrical plastic object like a syringe barrel. Flat foil wrapping techniques would present alignment problems.
Thus, there still remains a need for an improved scale on a plastic syringe barrel that eliminates secondary operations such as printing. This improved method should permanently and accurately position the scale on a plastic syringe barrel. It should also be able to provide a raised scale for tactile sensation or readability and slip-resistant holding of the syringe. Also, it should be adaptable to high volume commercial production. The improved scale would be able to be made in various materials and colors, and it would also have the ability to be printed from about 1.degree. to about 360.degree. around the plastic syringe barrel.